sound: usb: Increase maximum transfer buffer limit

In order to support higher bit rate like 384Khz
higher buffer sizes are required. Hence change
the max limit from 2 * PAGE_SIZE to 24 * PAGE_SIZE.

Change-Id: I9d57f3011fee086b2d54997d85bc9a37ccc07e4a
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>